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Testimony is an invaluable source of knowledge. We rely on the reports of those around us for everything from the ingredients in our food and medicine to the identity of our family members. Recent years have seen an explosion of interest in the epistemology of testimony. Despite the multitude of views offered, a single thesis is nearly universally accepted: testimonial knowledge is acquired through the process of transmission from speaker to hearer. In this book, Jennifer Lackey shows that this thesis is false and, hence, that the literature on testimony has been shaped at its core by a view that is fundamentally misguided. She then defends a detailed alternative to this conception of testimony: whereas the views currently dominant focus on the epistemic status of what speakers believe, Lackey advances a theory that instead centers on what speakers say. The upshot is that, strictly speaking, we do not learn from one another's beliefs - we learn from one another's words. Once this shift in focus is in place, Lackey goes on to argue that, though positive reasons are necessary for testimonial knowledge, testimony itself is an irreducible epistemic source. This leads to the development of a theory that gives proper credence to testimony's epistemologically dual nature: both the speaker and the hearer must make a positive epistemic contribution to testimonial knowledge. The resulting view not only reveals that testimony has the capacity to generate knowledge, but it also gives appropriate weight to our nature as both socially indebted and individually rational creatures. The approach found in this book will, then, represent a radical departure from the views currently dominating the epistemology of testimony, and thus is intended to reshape our understanding of the deep and ubiquitous reliance we have on the testimony of those around us.

The assumption that we largely lack reasons for accepting testimony has dominated its epistemology. Given the further assumption that whatever reasons we do have are insufficient to justify our testimonial beliefs, many conclude that any account of testimonial knowledge must allow credulity to be justified. In this paper I argue that both of these assumptions are false. Our responses to testimony are guided by our background beliefs as to the testimony as a type, the testimonial situation, the testifier''s character and the truth of the proposition testified to. These beliefs provide reasons for our responses. Thus, we usually do have reasons, in the sense of propositions believed, for accepting testimony and these reasons can provide evidence for the testimonial beliefs we form.

David Hume advances a reductionist epistemology of testimony: testimonial beliefs are justified on the basis of beliefs formed from other sources. This reduction, however, has been misunderstood. Testimonial beliefs are not justified in a manner identical to ordinary empirical beliefs; it is true, they are justified by observation of the conjunction between testimony and its truth, it is the nature of the conjunctions that has been misunderstood. The observation of these conjunctions provides us with our knowledge of human nature and it is this knowledge which justifies our testimonial beliefs. Hume gives a naturalistic rather than sceptical account of testimony.

In “Group Testimony” (2007) I argued that the testimony of a group cannot be understood (or at least cannot always be understood) in a summative fashion; as the testimony of some or all of the group members. In some cases, it is the group itself that testifies. I also argued that one could extend standard reductionist accounts of the justification of testimonial belief to the case of testimonial belief formed on the basis of group testimony. In this paper, I explore the issue of group testimony in greater detail by focusing on one putative source of testimony, that of Wikipedia. My aim is to the answer the following questions: Is Wikipedia a source of testimony? And if so, what is the nature of that source? Are we to understand Wikipedia entries as a collection of testimonial statements made by individuals, some subset of individuals, or is Wikipedia itself (the organization or the Wikipedia community) the entity that testifies? If Wikipedia itself is a source of testimony, what resources do we have for assessing the trustworthiness of such an unusual epistemic source? In answering these questions I hope to further elucidate the nature of collective epistemic agency (Tollefsen 2006), of which group testimony is a paradigm example. When a mans Discourse begineth…at some saying of another, of whose ability to know the truth, and of whose honesty in not deceiving, he doubteth not; and then the Discourse is not so much concerning the Thing, as the Person; and the Resolution is called Beleefe, and Faith: Faith in the man. (1651/1991, Ch. 7; p. 48).

In this paper, I apply Duncan Pritchard’s anti-luck epistemology to the case of knowledge through testimony. I claim (1) that Pritchard’s distinction between veritic and reflective luck provides a nice taxonomy of testimony cases, (2) that the taxonomic categories that emerge can be used to suggest precisely what epistemic statuses are transmissible through testimony, and (3) that the resulting picture can make clear how testimony can actually be knowledge-generating.

Extensive literatures exist on the epistemology of testimony, memory, and perception, but for the most part these literatures do not systematically consider the extent of the analogies between the three epistemic sources. A number of the same problems reappear in all three literatures, however. Dealing simultaneously with all three sources and making a careful accounting of the analogies and disanalogies between them should therefore avoid unnecessary duplication of effort. Other than limits on the scope of which memorially- and testimonially-based beliefs should be included in the Parity Thesis, I argue that most of the disanalogies that different philosophers have proffered between the sources do not mark distinctions among the universes of possible testimonially-, memorially-, and perceptually-based beliefs regarding the explanation of those beliefs' epistemic status. I first criticize the suggestion that perception is a generative epistemic source, while testimony and memory are not; I propose and defend counterexamples in which testimony and memory produce new beliefs. Next, I criticize a variety of distinctions that have been drawn between testimony and perception, taken chiefly from the reductionist-antireductionist literature on testimony. I criticize the suggestion that the conceptualization of content and the transparency of experience affect the epistemologies of testimony and perception in different ways. Regarding memory and testimony, I advocate modeling testimony on the legal relationship of a principal and an agent, arguing that law's apparatus used to analyze such situations suggests that using others' epistemic services in testimony will supply the same epistemic benefits and burdens as if we had performed those epistemic tasks personally and then relied only on memory. I apply this analysis to the transmission of defeaters in testimony. I argue that memory does feature the epistemic equivalent of a perceptual image and that both perceptually- and memorially-based beliefs can concern either the past or the present. Finally, I construct a set of six transformations that turn individual possible instances of perceptually-, memorially-, or testimonially-based beliefs into individual possible instances of the other two types of beliefs without changing the structure of those beliefs' epistemologies.

Chapter I: Testimony: The Problem word, pdf) Chapter I defines the framework for the discussion of the epistemology of testimony. Testimony is defined, strictly, as utterances that are meant to be believed on the teller’s say-so alone, not because of supporting arguments or any like considerations. A working analysis of this notion of testimony is given, based on Grice’s analysis of “non-natural meaning” in terms of the speaker’s intention to induce belief by means of the hearer’s recognition of that intention (Grice 1957). This analysis of testimony permits us to frame the problem of the epistemology of testimony, how testimony can justify us in believing what we are told.

It is undeniable that the assumption of sincerity is important to assertion, and that assertion is central to the transmission of beliefs through human testimony. Discussions of testimony, however, often assume that the epistemic importance of sincerity to testimony is that of a (fallible) guarantee of access to the actual beliefs of the speaker. Other things being equal, we would do as well or better if we had some kind of unmediated access to the beliefs of the other person, without the risks involved in the overt act of speaking, and the assumption of sincerity in speech is the closest we can come to this access. Contrary to this picture, I argue that sincerity has a quite different epistemic role to play in testimony than that of an indicator of the speaker's beliefs. The epistemology of testimony requires reference to the speaker as agent, and not just the speaker's beliefs, as well as a sense of 'expression of belief' that links it to the specifically addressive relation to another person.

Most epistemologists of testimony assume that testifying requires that the beliefs to which speakers attest are identical to the beliefs that hearers accept. I argue that this characterization of testimony is misleading. Characterizing testimony in terms of duplicating speaker/hearer belief unduly resticts the variety of beliefs that might be accepted from speaker testimony.

The fact that much of our knowledge is gained through the testimony of others challenges a certain form of epistemic individualism. We are clearly not autonomous knowers. But the discussion surrounding testimony has maintained a commitment to what I have elsewhere called epistemic agent individualism. Both the reductionist and the anti-reductionist have focused their attention on the testimony of individuals. But groups, too, are sources of testimony - or so I shall argue. If groups can be testifiers, a natural question to ask is whether our beliefs based on the testimony of groups are ever justified and whether such a justification is to be conferred inferentially or non-inferentially. I consider and dismiss the possibility of extending an anti-reductionist account of justification to our group testimonial beliefs. I also argue against a version of reductionism that would have our group testimonial beliefs justified only in so far as we were able to monitor the trustworthiness of members of the group. However, there are forms of reductionism that can be extended to make sense of the justification of our group testimonial beliefs. There are mechanisms for monitoring the trustworthiness and competency of a group (rather than its members) and, further, a variety of background beliefs allow us to assess the testimony of a group for reliability.